The invention relates generally to polycrystalline transparent ceramic articles and in particular to lutetium-based compositions for optical applications.
Ceramic materials, such as lutetium-based optical compositions, have many applications in scintillator, laser, and imaging technology. Optical applications often require a transparent processed form of the material to reduce light losses due to scattering and absorption. To that end, the processed form is generally desired to have a single phase microstructure. Moreover, in many applications the material is desired to emit light or other electromagnetic radiation within a particular wavelength range. Optical properties such as the wavelength range of the emission and the efficiency of light conversion can be regulated, or “tuned,” in optical materials by selective usage of one or more dopants and by adjusting the concentration of the dopants within the material.
Current applications often use monocrystalline optical materials, the making of which is quite expensive and time consuming. Moreover, optical tunability in single crystals is often hard to achieve due to the difficulty in doping during crystal formation.
An alternate method is to employ polycrystalline materials. The polycrystalline materials are more easily doped as compared to monocrystalline materials. The performance and utility of the polycrystalline materials depend in part on the size, shape, and morphology of the crystallites constituting the material which in turn may be controlled via processing.
The processing of polycrystalline ceramic materials to obtain a transparent form may require exposure to high temperature, during which a desirable microstructure may degrade due to such thermally activated processes as grain growth, phase transformation, and other related mechanisms. Therefore, there is a need to address these issues to provide an efficient, economical, and robust polycrystalline optical composition.